1. Field of the Invention
The present invention relates to a switching power-supply apparatus including power converters connected in parallel, and a droop characteristic correction method performed by the switching power-supply apparatus.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 8-289468 discloses a DC power-supply apparatus to perform parallel operation of a plurality of DC power supplies connected in parallel. The DC power-supply apparatus described in Japanese Unexamined Patent Application Publication No. 8-289468 performs droop control in which, as a detected output current of a DC power supply increases, an output voltage is reduced. At this time, when droop characteristics of the respective DC power supplies vary, there is a risk that currents concentrate on one DC power supply, an overcurrent state occurs, and more heat is generated. In addition, there is a risk that a maximum output power of the entire apparatus falls below an expected value. Accordingly, it is important to control load factors of the respective DC power supplies to be even.
As described above, when each of the plurality of DC power supplies performs the droop control, the droop characteristics may vary due to variations in characteristics of individual components. Thus, it may be considered, for example, before factory shipment, to calculate a correction value from a detection result of an output voltage with respect to an output current, store the correction value in a memory, and correct a droop characteristic using the stored correction value when actually used. However, in Japanese Unexamined Patent Application Publication No. 8-289468, only a total output current of the plurality of DC power supplies connected in parallel is detectable. Accordingly, the same correction value is to be used for droop characteristics set for each of the plurality of DC power supplies. As a result, it is difficult to correct variations in detection results of output currents of the respective DC power supplies separately and precisely.